The following commit has been merged in the batadv/net-next branch: commit 75c498b4d473936c54a7f691f39dbc93fe0ba263 Author: Remi Pommarel repk@triplefau.lt Date: Wed Nov 20 18:47:17 2024 +0100

batman-adv: Remove atomic usage for tt.local_changes

The tt.local_changes atomic is either written with tt.changes_list_lock or close to it (see batadv_tt_local_event()). Thus the performance gain using an atomic was limited (or because of atomic_read() impact even negative). Using atomic also comes with the need to be wary of potential negative tt.local_changes value.

Simplify the tt.local_changes usage by removing the atomic property and modifying it only with tt.changes_list_lock held.

Signed-off-by: Remi Pommarel repk@triplefau.lt Signed-off-by: Sven Eckelmann sven@narfation.org Signed-off-by: Simon Wunderlich sw@simonwunderlich.de

diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c index 2758aba47a2f2..2575f13992d27 100644 --- a/net/batman-adv/soft-interface.c +++ b/net/batman-adv/soft-interface.c @@ -783,13 +783,13 @@ static int batadv_softif_init_late(struct net_device *dev) atomic_set(&bat_priv->mesh_state, BATADV_MESH_INACTIVE); atomic_set(&bat_priv->bcast_seqno, 1); atomic_set(&bat_priv->tt.vn, 0); - atomic_set(&bat_priv->tt.local_changes, 0); atomic_set(&bat_priv->tt.ogm_append_cnt, 0); #ifdef CONFIG_BATMAN_ADV_BLA atomic_set(&bat_priv->bla.num_requests, 0); #endif atomic_set(&bat_priv->tp_num, 0);

+ bat_priv->tt.local_changes = 0; bat_priv->tt.last_changeset = NULL; bat_priv->tt.last_changeset_len = 0; bat_priv->isolation_mark = 0; diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c index 4c11d708f3cc6..aa5c44e114190 100644 --- a/net/batman-adv/translation-table.c +++ b/net/batman-adv/translation-table.c @@ -423,7 +423,6 @@ static void batadv_tt_local_event(struct batadv_priv *bat_priv, struct batadv_tt_change_node *tt_change_node, *entry, *safe; struct batadv_tt_common_entry *common = &tt_local_entry->common; u8 flags = common->flags | event_flags; - bool event_removed = false; bool del_op_requested, del_op_entry;

tt_change_node = kmem_cache_alloc(batadv_tt_change_cache, GFP_ATOMIC); @@ -468,21 +467,17 @@ static void batadv_tt_local_event(struct batadv_priv *bat_priv, del: list_del(&entry->list); kmem_cache_free(batadv_tt_change_cache, entry); + bat_priv->tt.local_changes--; kmem_cache_free(batadv_tt_change_cache, tt_change_node); - event_removed = true; goto unlock; }

/* track the change in the OGMinterval list */ list_add_tail(&tt_change_node->list, &bat_priv->tt.changes_list); + bat_priv->tt.local_changes++;

unlock: spin_unlock_bh(&bat_priv->tt.changes_list_lock); - - if (event_removed) - atomic_dec(&bat_priv->tt.local_changes); - else - atomic_inc(&bat_priv->tt.local_changes); }

/** @@ -952,7 +947,7 @@ static void batadv_tt_tvlv_container_update(struct batadv_priv *bat_priv) size_t tt_extra_len = 0; u16 tvlv_len;

- tt_diff_entries_num = atomic_read(&bat_priv->tt.local_changes); + tt_diff_entries_num = READ_ONCE(bat_priv->tt.local_changes); tt_diff_len = batadv_tt_len(tt_diff_entries_num);

/* if we have too many changes for one packet don't send any @@ -980,7 +975,7 @@ static void batadv_tt_tvlv_container_update(struct batadv_priv *bat_priv) tt_data->flags = BATADV_TT_OGM_DIFF;

spin_lock_bh(&bat_priv->tt.changes_list_lock); - atomic_set(&bat_priv->tt.local_changes, 0); + bat_priv->tt.local_changes = 0;

list_for_each_entry_safe(entry, safe, &bat_priv->tt.changes_list, list) { @@ -1396,7 +1391,7 @@ static void batadv_tt_changes_list_free(struct batadv_priv *bat_priv) kmem_cache_free(batadv_tt_change_cache, entry); }

- atomic_set(&bat_priv->tt.local_changes, 0); + bat_priv->tt.local_changes = 0; spin_unlock_bh(&bat_priv->tt.changes_list_lock); }

@@ -3657,7 +3652,7 @@ static void batadv_tt_local_commit_changes_nolock(struct batadv_priv *bat_priv) { lockdep_assert_held(&bat_priv->tt.commit_lock);

- if (atomic_read(&bat_priv->tt.local_changes) < 1) { + if (READ_ONCE(bat_priv->tt.local_changes) < 1) { if (!batadv_atomic_dec_not_zero(&bat_priv->tt.ogm_append_cnt)) batadv_tt_tvlv_container_update(bat_priv); return; diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h index 04f6398b3a40e..f491bff8c51b8 100644 --- a/net/batman-adv/types.h +++ b/net/batman-adv/types.h @@ -1022,7 +1022,7 @@ struct batadv_priv_tt { atomic_t ogm_append_cnt;

/** @local_changes: changes registered in an originator interval */ - atomic_t local_changes; + size_t local_changes;

/** * @changes_list: tracks tt local changes within an originator interval @@ -1044,7 +1044,7 @@ struct batadv_priv_tt { */ struct list_head roam_list;

- /** @changes_list_lock: lock protecting changes_list */ + /** @changes_list_lock: lock protecting changes_list & local_changes */ spinlock_t changes_list_lock;

/** @req_list_lock: lock protecting req_list */